function s1_generate_a_series_of_files(){
    for i in {1..100};do echo $i>tmp/new_file$i;done
}
function s2_list_4_files_in_long_format_about_accountr_and_group(){
    ls -1 /etc/{passwd,shadow,group,gshadow} | sort -d
}
function s3_find_items_related_to_given_username(){
   grep -h $1 /etc/{passwd,shadow} | sort -d
}
function s4_find_items_related_to_given_username(){
    grep -h $1/etc/{group,gshadow} | sort -d
}
function s5_create_geoups_for_given_group_names(){
    groupadd rnd && groupadd itoperati
}
function s5_create_groups_for_given_group_names(){
    groupadd rnd && groupadd itoperati
}
function s6_create_users_and__set_their_group_as_required(){
    useradd -G rnd adam && useradd -G rnd bob && useradd -G itoperation calvin && useradd -Gitoperation david && useradd -G rnd edward
}
function s7_change_users_shell(){
    usermod -s /usr/bin/sh adam && usermod -s /usr/bin/sh edward
}
function s8_set_password_change_policy(){
    passwd -n 10 -X 60 -w 10 adam
    passwd -n 10 -x 60 -w 10 bob
    passwd -n 10 -x 60 -w 10 david
    passwd -n 10 -x 60 -w 10 calvin
    passwd -n 10 -x 60 -w 10 edward
}
function s9_set_password_for_five_users(){
    username=(adam bob calvin david edward)
    for i in $(seq 1 5);do echo ${!i};echo $(($i-1));done
    echo "${usernames[0]}:$1" | chpasswd
    echo "${usernames[1]}:$2" | chpasswd
    echo "${usernames[2]}:$3" | chpasswd
    echo "${usernames[3]}:$4" | chpasswd 
    echo "${usernames[$(($i-1))]}:$5" | chpasswd
}
function s10_lock_bobs_password(){
  usermod -L bob
}
function s11_include_adam_into_wheel_group(){
  usermod -a -G wheel adam
}
function s12_change_files_permission(){
  for i in {1..33};do chmod -R 640 /tmp/new_file$[3*i];done
}
